RX7Vert91'

Ok I am a 7 guy and been looking at a engine swap and I have wanted to do a RENESIS, now as always when I did a swap talk on the 7 boards I got just do a TII swap and then the V8 guys started talking and well we got in a fight and it got closed down… any way so I got myself over here to talk to guys who have done work on REN’s and if I do go this way I want to try to supercharger... any way anyone got pros con's for the REN?

Thanks
Zane

Transam kid 01

iTrader: (1)

Check out the major HP upgrades section

04RX8man

there are plenty of ppl around the forum with FI....like transamkid said check out the major HP section ALOT of good readups over there....

Brettus

iTrader: (2)

The biggest pros for a renesis is drivability . IT will idle nice and get better fuel consumption (than earlier 13bs). Plenty here have turboed and SCd the renesis to good effect .
It is only recently that some decent hp numbers are being made due to taking years to get around the ECU . 350whp is not too hard to get now on stock internals but has only been done with a turbo so far ....
Only real con is that it is fragile and is easily blown if tuning and supporting mods are not spot on

RX7Vert91'

thanks guys.

SayNoToPistons

iTrader: (8)

There is a flaw to that statement.

Brettus

iTrader: (2)

/\ and that would be ...... ?

SayNoToPistons

iTrader: (8)

Quite a few RX7 guys manage to get 20+ MPG with their turbo and non turbo rotaries. Our 13B-MSP isn't as big of an improvement when it comes to gas consumption as you think.

Brettus

iTrader: (2)

maybe true but how heavy are RX7s ?

A renesis in a 7 should do better than in an 8

dmorales

Ahh, good point.

I believe 7's are somewhere near the 2800lb mark...so slight advantage.
________
My Green Heaven Ministry Millbrae

RX7Vert91'

FC are only 2,600 lbs God there not fat... who would want a sports car that much weight and for me to then take off the motors for the top and a few other small things, I think I could get a few hundred more off without compensating comfort and hell I might get better then 25 MPG haha And I dont know of anyone who has done a REN swap in to a vert so I get to have fun and be one of the firsts.

LionZoo

Have you actually weighed your convertible? If I remember correctly the FC convertible is the heaviest rotary that Mazda has built. The 2,600 pound figure is for the earliest coupe FCs.

Chibana

The other difference would be lowered emissions, I would think. It seems to me that this engine swap is more trouble than it's worth, unless you have to replace your engine, anyway.

Brettus

iTrader: (2)

on second thoughts - you will need to run a stand alone pcm in which case you will struggle to get the mpg that the Renesis is capable of ..

04RX8man

the most HP on a S/C renny IN PERSON is like 303WHP.....

RotaryResurrection

iTrader: (3)

Lot of misinformation so far.

The 89-91 convertible was the heaviest rx7 ever made. Should tip the scales in the 3050-3100lb range in stock form. Typical exhaust and engine bay modifications might save you 100lb off of that figure. So basically, the weight of the convertible will be around the same as the weight of the rx8, and thus performance should also stay the same. Except of course that the gearing in your convertible is taller than the rx8, so you may see slightly better mpg but you also will see slightly lower acceleration.

The renesis and the rx7 engines are rated for about the same mpg in stock form, plus or minus a couple of mpg which can be made up for in driving style. Me personally I have yet to see 20mpg out of an rx8 in stock/near stock form on the stock PCM tuning. I have gotten WELL in excess of 20mpg with tuned rx7 setups. My personal 466rwhp FC gets about 23mpg on the highway at 75-80mpg. A mostly stock/lightly modded FD can get 25mpg on the highway at 75. My personal rx8 gets about 19mpg on the highway at the same speeds. Both cars have recently built, tight engines and the full spread of maintenance.

The renesis is light years ahead of the older rotaries as far as emissions. However, a new Camry is light years ahead of a renesis as far as emissions, and we do not drive these cars/engines for emissions anyway, so I see this as a moot point.

The stock rx7 non turbo engine could go 140-200k miles ROUTINELY. That means that the greatest percentage of them made it that far before failing, with a few exceptions on both sides of that number.

The stock renesis seems to be going 50-85k miles before failing. Again, the largest percentage seems to fall within those numbers from what I can see, with some examples on both sides (some failing sooner, some lasting longer). Why this is, I have several theories for. These include the higher average rpm that the renesis turns due to the rx8 gearing (similar to 1st gen rx7 gearing), insufficient oil recommendation by mazda, insufficient OMP injection ratio (and location), and too small an oilpan/oil capacity in stock form.

A few have modded renesis engines to make >300rwhp. But this is the exception at this point. It also costs WAAAAAYYYYY more than it would to mod an 87-95 rx7 turbo setup for the same power level. IT also requires far more non-user-friendly electronic intervention than the older setups. And finally I would dare say that a boosted 300+hp renesis is less reliable than an equivalently powerful rx7 turbo engine setup.

The renesis internals actually seem to be a step down from the rx7 stuff in terms of strength. The rotors are lightened slightly versus the 89-95 rx7 stuff, but they are also thin, and do not SAFELY allow for any significant machining (to accept larger/better seals). The irons seem to be cast differently not to allow for any significant porting at all, and the material seems to be softer which lends the dowelpin areas to cracking under higher power. The rotor housings do not seem to wear (chrome flake) as much as the rx7 housings, however they do develop severe cracks around the inside of the leading sparkplug holes at relatively low mileage. I feel this is due to the high consistent rpm of the renesis/rx8 gearing, and a slightly insufficient cooling system (waterpump/radiator capacity).

Brettus

iTrader: (2)

/\ party pooper

nycgps

iTrader: (1)

So RR, I guess I made a pretty good choice on the 91 NA FC Then

yeah its all beat up piece of crap and cost me couple grand in parts. But hmm it seems that it will last ...